In recent years, the method of contactlessly supplying electrical energy to wireless power receivers in a wireless manner has been used instead of the traditional method of supplying electrical energy in a wired manner. The wireless power receiver receiving energy in a wireless manner may be directly driven by the received wireless power, or a battery may be charged by using the received wireless power, then allowing the wireless power receiver to be driven by the charged power.
The Wireless Power Consortium (WPC) which manages technologies for a magnetic inductive wireless power transfer has published a standard document “System description Wireless Power Transfer, Volume 1, Low Power, Part 1: Interface Definition, Version 1.00 Release Candidate 1 (RC1)” for interoperability in the wireless power transfer on Apr. 12, 2010.
A transmitter (a transfer device, a transmitting apparatus, etc.) may transmit power to a receiver (a receiving device, a receiving apparatus, etc.) by a one-to-one unidirectional communication method in which one transmitter and one receiver communicate with each other in one-to-one correspondence. However, when one transmitter has to communicate with a plurality of receivers, difficulty in communication may be caused in the related art method.